U.S. patent number 6,736,818 [Application Number 10/141,835] was granted by the patent office on 2004-05-18 for radially expandable intramedullary nail.
This patent grant is currently assigned to Synthes (U.S.A.). Invention is credited to Markus Hehli, Stephan Perren.
United States Patent |
6,736,818 |
Perren , et al. |
May 18, 2004 |
Radially expandable intramedullary nail
Abstract
The invention is related to an intramedullary nail for fixation
of a fractured bone having a medullary canal. The intramedullary
nail may comprise a first radially expandable section provided in a
proximal section adjacent to the head of the intramedullary nail, a
second radially expandable section provided in the distal section
adjacent to the tip of the intramedullary nail, and a
non-expandable middle section provided between said two radially
expandable sections of the intramedullary nail. The head may
provide a distraction mechanism, by means of which said two
radially expandable sections are distractible transverse to said
longitudinal axis.
Inventors: |
Perren; Stephan (Davos Dorf,
CH), Hehli; Markus (Frauenkirch, CH) |
Assignee: |
Synthes (U.S.A.) (Paoli,
PA)
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Family
ID: |
4551732 |
Appl.
No.: |
10/141,835 |
Filed: |
May 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCTCH9900532 |
Nov 11, 1999 |
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Current U.S.
Class: |
606/63; 606/60;
606/62 |
Current CPC
Class: |
A61B
17/7266 (20130101) |
Current International
Class: |
A61B
17/72 (20060101); A61B 17/68 (20060101); A61B
017/58 () |
Field of
Search: |
;606/63,60,62,66,67,68,72 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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587 317 |
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Oct 1933 |
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DE |
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38 35 682 |
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Apr 1990 |
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DE |
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0 086 552 |
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Aug 1983 |
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EP |
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0 094 039 |
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Nov 1983 |
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EP |
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2268068 |
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Jan 1994 |
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GB |
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1071298 |
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Feb 1984 |
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SU |
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1337074 |
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Sep 1987 |
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SU |
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WO 97/18769 |
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May 1997 |
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WO |
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WO 98/05263 |
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Feb 1998 |
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WO |
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Other References
W L. Pugh, "A Self-Adjusting Nail-Plate for Fractures About the Hip
Joint," J. Bone Joint Surg. 37-A:1085-93, (1955). .
Richards et al., "The AO Dynamic HIP Screw and the Pugh Sliding
Nail in Femoral Head Fixation," J. Bone Joint Surg. [Br]
72-B:794-6, (1990). .
Jarrett et al., "The stable internal fixation of peritrochanteric
hip fractures," Part V (pp. 203-218). .
Calandruccio et al., "Internal Fixation Devices for Fractures of
the Proximal Femur American Academy of Orthopaedic Surgeons
Committee on the History of Orthopaedic Surgery," Brochure (pp.
1-7). .
William K. Massie, M.D., "Extracapsular Fractures of the Hip
Treated by Impaction Using a Sliding Nail-plate Fixation," Chapter
18 (pp. 180-201)..
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Primary Examiner: O'Connor; Cary E.
Assistant Examiner: Melson; Candice C.
Attorney, Agent or Firm: Jones Day
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of the U.S. national stage
designation of copending International Patent Application
PCT/CH99/00532, filed Nov. 11, 1999, the entire content of which is
expressly incorporated herein by reference thereto.
Claims
What is claimed is:
1. An intramedullary nail having a head, a tip, and a longitudinal
axis for fixation of a fractured bone having a medullary canal, the
intramedullary nail comprising: a first radially expandable section
adjacent to the head; a second radially expandable section adjacent
to the tip; and a non-expandable section disposed between the first
and second radially expandable sections; wherein the first and
second radially expandable sections each comprise a slotted tubular
member.
2. The intramedullary nail of claim 1, wherein the head is provided
a distraction mechanism, and the first and second radially
expandable sections are distractible transverse to said
longitudinal axis.
3. The intramedullary nail of claim 1, wherein the non-expandable
section has a length in the range of about 10 mm to 25 mm.
4. The intramedullary nail of claim 1, wherein the slotted tubular
members are configured to be slidable on the sleeve.
5. The intramedullary nail of claim 1, wherein the non-expandable
section comprises one unslotted tubular member.
6. The intramedullary nail of claim 5, wherein the non-expandable
section of the intramedullary nail has a length in the range of
about 15 mm to about 22 mm.
7. The intramedullary nail of claim 1, further comprising a hollow
cylindrical sleeve extending along the longitudinal axis and
surrounding a locking element coaxially to the longitudinal
axis.
8. The intramedullary nail of claim 7, wherein the locking element
comprises a shaft with a thread in a proximal section and a
projection forming an abutment in the a distal section.
9. The intramedullary nail of claim 7, wherein the sleeve comprises
means for engagement of a holding means.
10. The intramedulllary nail of claim 9, wherein the means for
engagement of a holding means is a slot.
11. The intramedullary nail of claim 7, wherein the head is
provided with a distraction mechanism comprising a thread on the
locking element adjacent to the head and a nut with an interior
thread corresponding with the thread on the locking element.
12. The intramedullary nail of claim 11, wherein the nut comprises
means for engagement of a driving means.
13. The intramedullary nail of claim 7, wherein the locking element
comprises means for engagement of a holding means.
14. The intramedullary nail of claim 13, wherein the head is
provided with a distraction mechanism comprising a thread on the
locking element adjacent to the head and an end cap with an
interior thread corresponding with the thread on the locking
element.
15. The intramedullary nail of claim 14, wherein the end cap
comprises means for engagement of a driving means.
16. An intramedullary nail having a head, a tin, and a longitudinal
axis for fixation of a fractured bone having a medullary canal, the
intramedullary nail comprising: a first radially expandable section
adjacent to the head; a second radially expandable section adjacent
to the tip; and a non-expandable section disposed between the first
and second radially expandable sections; wherein the expandable and
non-expandable sections are tubular members that are positioned
over the sleeve in sequence and are secured on the sleeve by a nut,
the sequence of positioning the tubular members comprising: a
slotted tubular member, an unslotted tubular member, a slotted
tubular member, and an unslotted tubular member.
17. The intramedullary nail of claim 16, wherein the nut comprises
means for engagement of a driving means.
18. The intramedullary nail of claim 17, wherein the means for
engagement of a driving means comprises hexagonal sides.
19. An intramedullary nail having a head, a tip, and a longitudinal
axis for fixation of a fractured bone having a medullary canal, the
intramedullary nail comprising: a first radially expandable section
adjacent to the head; a second radially expandable section adjacent
to the tip; a non-expandable section disposed between the first and
second radially expandable sections; and a hollow cylindrical
sleeve extending along the longitudinal axis and surrounding a
locking element coaxially to the longitudinal axis; wherein the
locking element comprises a shaft with a thread in a proximal
section and a projection forming an abutment in a distal section;
and wherein a distal section of the sleeve provides a slot
penetrating a side wall through to a bore and the projection of the
locking element is movable to slide within said slot in the
direction of the longitudinal axis.
20. An intramedullary nail for fixation of a fractured bone having
a medullary canal, the intramedullary nail comprising: a central
member comprising a proximal section with a head, a distal section
with a tip, and a longitudinal axis; a first radially expandable
member slidably disposed on the proximal section of the central
member; a second radially expandable member slidably disposed on
the distal section of the central member; and a non-expandable
section slidably disposed on the central member between the first
and second radially expandable sections.
21. The intramedullary nail of claim 20, wherein the first and
second radially expandable sections each comprise a slotted tubular
member.
22. The intramedullary nail of claim 20, wherein the head is
provided with a distraction mechanism, and the first and second
radially expandable sections are distractible with respect to each
other.
23. The intramedullary nail of claim 20, wherein the non-expandable
section comprises at least one unslotted tubular member.
24. The intramedullary nail of claim 20, wherein the non-expandable
section has a length in the range of about 10 mm to 25 mm.
25. The intramedullary nail of claim 20, wherein the non-expandable
section has a length in the range of about 15 mm to about 22
mm.
26. The intramedullary nail of claim 20, wherein the head is
provided with a distraction mechanism comprising a threaded portion
and a nut threadably associated therewith.
27. The intramedullary nail of claim 26, wherein the nut comprises
means for engagement of a driving means.
28. The intramedullary nail of claim 20, further comprising a
hollow cylindrical sleeve disposed about the longitudinal axis and
surrounding a shaft comprising a thread in a proximal section and a
projection forming an abutment in the distal section.
29. The intramedullary nail of claim 28, wherein a distal section
of the sleeve comprises a slot extending to a bore therein an the
projection of the shaft is slidable within the slot in the
direction of the longitudinal axis.
30. The intramedullary nail of claim 20, further comprising a
hollow cylindrical sleeve extending about the longitudinal axis and
surrounding a locking element.
31. The intramedullary nail of claim 30, wherein the expandable and
non-expandable sections are tubular members that are disposed on
the sleeve in sequence and are secured on the sleeve by a nut, the
sequence comprising: a slotted tubular member, an unslotted tubular
member, and a slotted tubular member.
32. The intramedullary nail of claim 31, wherein the nut comprises
means for engagement of a driving means.
33. The intramedullary nail of claim 32, wherein the means for
engagement of a driving means comprises hexagonal sides.
Description
FIELD OF THE INVENTION
The present invention relates generally to orthopaedic fixation
devices, and in particular to a fixation system for bones having an
intramedullary canal.
BACKGROUND OF THE INVENTION
Various types of intramedullary nails are already known in the
state of the art, which are expandable in a limited section of the
nail in order to allow the fixation of the nail against the bone
cortex, e.g. by means of radially deploying a number of blades in
the distal portion of the intramedullary nail. These devices,
however, when in use may lead to clinical results that are not
optimally consistent with the state of the art concept of fracture
treatment. For instance, an intramedullary nail which is not
extrafocal may negatively affect endosteal vascularisation in the
fracture area because the largest expansion of the nail is in the
fracture area. Also, the largest expansion of the nail in the
fracture area may generate forces which may have the tendency to
separate fragments in comminuted fractures or, in the case of
longitudinal non-dislocated fractures to increase the gap and to
dislocate fragments which may lead to loosening of the fixation.
Thus, despite these developments, a need exists for a nail having
expandable parts which may be located extrafocally, leaving the
fracture area less affected from radial forces. Such a nail might
be particularly strong in the middle part--between the proximal and
distal sections--of the nail and might not require the use of
fluoroscopy for distal nor proximal locking.
SUMMARY OF THE INVENTION
The invention in one embodiment is related to an intramedullary
nail having a head, a tip, and a longitudinal axis for fixation of
a fractured bone having a medullary canal. The intramedullary nail
may comprise a hollow cylindrical sleeve extending along the
longitudinal axis and surrounding a locking element coaxially to
the longitudinal axis. The nail may further include a first
radially expandable section adjacent to the head, a second radially
expandable section adjacent to the tip, and a non-expandable
section disposed between the first and second radially expandable
sections. The head of the intramedullary nail may be provided with
a distraction mechanism, by means of which the first and second
radially expandable sections are distractible transverse to said
longitudinal axis. The non-expandable section may comprise at least
one unslotted tubular piece. In one embodiment of the
intramedullary nail the non-expandable section has a length in the
range of 10 to 25 mm. In another embodiment, the non-expandable
section of the intramedullary nail has a length in the range of
about 15 mm to about 22 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred features of the present invention are disclosed in the
accompanying drawings, wherein similar reference characters denote
similar elements throughout the several views, and wherein:
FIG. 1 shows a schematic representation of an intramedullary nail
of the present invention in the non-expanded state;
FIG. 2 shows an exploded view of the intramedullary nail according
to FIG. 1;
FIG. 3 shows a schematic representation of one of the expandable
sections of the intramedullary nail of FIG. 1 in the non-expanded
and in the expanded state;
FIG. 4 shows a schematic representation of an intramedullary nail
of the present invention in the expanded state;
FIG. 5 shows a second embodiment of an intramedullary nail of the
present invention in the non-expanded state.
FIG. 6 shows a variation of the nut to be used with the
intramedullary nail of FIG. 5;
FIG. 7 shows a third embodiment of an intramedullary nail of the
present invention and in the non-expanded state;
FIG. 8 shows the intramedullary nail of FIG. 7 in the expanded
state;
FIG. 9 shows the intramedullary nail of FIG. 7 implanted in a femur
bone and in the expanded state
FIG. 10 shows a fourth embodiment of an intramedullary nail of the
present invention in the expanded state; and
FIG. 11 shows a the intramedullary nail of FIG. 10 implanted in a
femur bone and in the expanded state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For convenience, the same or equivalent elements in the various
embodiments of the invention illustrated in the drawings have been
identified with the same reference numerals. Further, in the
description that follows, any reference to either orientation or
direction is intended primarily for the convenience of description
and is not intended in any way to limit the scope of the present
invention thereto.
FIGS. 1-4 show a first embodiment of the invention which comprises
a solid nail core 10 with a head 1 and a tip 2 and a longitudinal
axis 3. In the proximal section 4 adjacent to head 1 a thread 9 is
provided. The middle section 8 of core 10 has a smooth surface 13
and a diameter tapering towards the distal section 6 adjacent to
tip 2. The middle section 8 of core 10 and the end section 11 of
the core 10 are separated by an annular abutment 12, and end
section 11 has a larger diameter than middle section 8.
As shown in FIG. 2, the following elements are slid over core 10 in
the following sequence: a slotted tubular piece 14; an unslotted
tubular piece 15; a slotted tubular piece 16; an unslotted tubular
piece 17; and, a nut 18 with an inner thread corresponding with
thread 9. When these elements are aligned on core 10, a screwing of
nut 18--by means of the two parallel sides or hexagonal sides
22--on thread 9 and counter holding the core 10--by means of slot
23--will produce an axial force or compression (as indicated by
arrows 19 in FIG. 3) on tubular pieces 17,16,15,14 as the slotted
tubular piece 14 abuts against abutment 12 of core 10. As shown in
FIG. 3, the cuts 20 of slotted tubular piece 14--as well as those
of slotted tubular piece 16--will cause an expansion of slotted
tubular piece 14 by radially deforming the belts 21 located between
the cuts 20.
As shown in FIG. 4, the nail is expandable at a first radially
expandable section 5 in proximal section 4 adjacent to head 1 of
the nail and in a second radially expandable section 7 in distal
section 6 adjacent to tip 2 of the nail. In an alternate
embodiment, instead of the two parallel sides or hexagonal sides 22
and the slot 23 for tightening the nut 18, two hexagon sockets may
be placed.
FIG. 5 and FIG. 6 show a second embodiment of the intramedullary
nail different from the embodiment shown in FIGS. 1-4, and it
provides instead of the core 10, a hollow cylindrical sleeve 35
extending along the longitudinal axis 3 and surrounding a locking
element 32 coaxially to longitudinal axis 3. The locking element 32
comprises a shaft with a thread 41 in the proximal section 4, and
in distal section 6, a projection 31 forming an abutment 39. In the
distal section 6 of sleeve 35, a slot 34 is provided penetrating
the side wall through to bore 33 such that projection 31 of locking
element 32 may slide within slot 34 in the direction of the
longitudinal axis 3. The following elements are slid over sleeve 35
in the following sequence: a slotted tubular piece 14; an unslotted
tubular piece 15; a slotted tubular piece 16; an unslotted tubular
piece 17; an end cap 42; and, a nut 40 with an inner thread
corresponding with thread 41.
Once these elements are aligned on sleeve 35 the tightening of nut
40 on thread 41 while counter holding locking element 32, by means
of the hexagon socket 43, axially compresses the tubular pieces
14,15,16,17 as the slotted tubular piece 14 abuts against abutment
39 formed by the projection 31 of locking element 32. As described
above in the first embodiment, belts 21 of the slotted tubular
pieces 14,16 buckle and radially expand under the axial forces 19
(FIG. 3). In an alternative embodiment, instead of nut 40 and end
cap 42, another end cap 36 providing interior thread 38
corresponding with thread 41 and a hexagon socket 37 may be used
(FIG. 6).
FIGS. 7-9 show a third embodiment of the intramedullary nail which
basically comprises five elements: a nut 50, a hollow proximal
section 51, a hollow middle section 52 and a hollow distal section
53 and a central wire 54. Contact between proximal section 51 and
middle section 52 is represented by transverse abutments 55
(relative to the longitudinal axis 3). Contact between middle
section 52 and distal section 53 is represented by transverse
abutments 56 (relative to the longitudinal axis 3). Central wire 54
is fixed in distal section 53 and runs through the hollow channel
59 of sections 51,52,53. At its proximal end, central wire 54 has
threads 57 which correspond to the interior threads 58 of nut 50.
When the nut 50 is turned by means of a key 60, the central wire 54
is tightened and produces sliding of the proximal section 51 and
distal section 53 on the transverse abutments 55 and 56
respectively. If the intramedullary channel 61 of the femur 62
(FIG. 9) is larger in diameter than the intramedullary nail, the
proximal section 51 and distal section 53 will expand radially
until firm fixation of the bone fragments 63 and 64. This radial
expansion is possible because the transverse abutments 55,56
enclose an angle of between 5.degree. and 85.degree. with the
longitudinal axis 3 such that upon applying a force in the axial
direction by means of tightening nut 50, the proximal section 51,
middle section 52, and the distal section 53 slide on abutments
55,56. Because the abutments 55,56 enclose an angle with the
longitudinal axis 3 the sections 51;52;53 opposing each other at
one abutment 55;56 each provide a sliding component orthogonal to
the longitudinal axis 3 what causes a radial expansion of the
intramedullary nail. The sharp radial teeth 65 in middle section 52
prevent axial displacement of the bone fragments 63,64 after its
fixation.
FIG. 10 and FIG. 11 show a fourth embodiment of the intramedullary
nail which basically comprises three elements: a nut 71 with head 1
and conical tip 78, a central wire 72 with a cone like distal end
73, and a hollow intramedullary nail 73. The ends of intramedullary
nail 73 are provided with a plurality of cuts 74. Central wire 72
runs through the hollow channel 75 of intramedullary nail 73
and--at its proximal end--has threads 76 which correspond to the
interior threads 77 of nut 71. When nut 71 is turned by means of a
key 60, the distance between the conical tip 78 of nut 71 and the
cone-like distal end 73 of central wire 72 is shortened, so that
cuts 74 of intramedullary nail 73 are expanded as shown in FIG. 11.
The expansion of intramedullary nail 73 proximally and distally at
sections 5 and 7 produces a firm fixation of the bone fragments 63
and 64 of femur 62.
The intramedullary nail may comprise a first radially expandable
section provided in the proximal section adjacent to the head of
the intramedullary nail, a second radially expandable section
provided in the distal section adjacent to the tip of the
intramedullary nail and a non-expandable middle section provided
between said two radially expandable sections of the intramedullary
nail. The head may provide a distraction mechanism, by means of
which said two radially expandable sections are distractible
transverse to said longitudinal axis.
In a preferred embodiment of the intramedullary nail, the
non-expandable section of the intramedullary nail may have a length
in the range of about 10 mm to about 25 mm, preferably in the range
of about 15 mm to about 22 mm. Furthermore, the intramedullary nail
may consist of a solid nail core with a head and a tip. In the
proximal section adjacent to the head a thread may be provided. The
middle section of the core may be configured with a smaller
diameter than the end section of the core such that the middle
section and the end section are separated by an annular abutment.
Apart from the core, the intramedullary nail in one embodiment may
comprise: two longitudinally slotted tubular pieces that provide
first and second radially expandable sections; two unslotted
tubular pieces; and, a nut.
These elements may be slid over the core in the following sequence:
a slotted tubular piece; an unslotted tubular piece; a slotted
tubular piece; and, an unslotted tubular piece such that adjacent
to the tip of the nail a first slotted tubular piece might be
provided. The second slotted tubular piece may be separated from
the first one by means of an unslotted tubular piece. For instance,
adjacent to the end of the nail a nut with an interior thread
corresponding to a thread on the core may be mounted to compress
the tubular pieces along the longitudinal axis. When these element
are aligned on the core a screwing of the nut onto the thread on
the core--by means of a driving means such as a spanner, wrench or
similar tool engaged to suitable means at the nut such as two
parallel sides, hexagonal sides, a hexagon socket or the like--and
holding up the core against rotation--by means of a second tool
inserted into corresponding suitable means at the core such as a
slot, hexagon socket or the like--may produce an axial force or
compression on the tubular pieces as the first slotted tubular
piece abuts against the abutment of the core and the nut is
tightened. Under that compression force the belts between the cuts
at the slotted tubular pieces may begin to buckle and deform
radially, causing a radial expansion of the slotted tubular pieces.
By this effect the nail may expand at a first radially expandable
section in the proximal section adjacent to the head of the nail
and in a second radially expandable section in the distal section
adjacent to the tip of the nail.
Another embodiment of the intramedullary nail may have, instead of
the core, a hollow cylindrical or prismatical sleeve extending
along the longitudinal axis and surrounding a rodlike locking
element coaxially to the longitudinal axis. The locking element may
comprise a shaft with a thread in the proximal section towards the
head of the nail and a projection forming an abutment in the distal
section. In the distal section the sleeve may provide a slot
penetrating the side wall through to the bore such that the
projection of the locking element may slide within the slot in the
direction of the longitudinal axis. Once the tubular elements are
aligned on the sleeve as mentioned above the tightening of the nut
on the thread on the locking element while holding up the locking
element against rotation may cause a compression force onto the
tubular elements clamped between the nut and the abutment producing
the same effect as described in the above embodiment of the
intramedullary nail.
A third preferred embodiment of the intramedullary nail may
comprise five elements: a nut; a hollow proximal section; a hollow
middle section; a hollow distal section; and, a central wire.
Contact between the proximal section and the middle section may be
represented by first abutments transversely arranged relative to
the longitudinal axis while contact between the middle section and
the distal section may be represented by second abutments
transversely arranged relative to the longitudinal axis. The
central wire may be fixed in the distal section and run through a
hollow channel of the other sections. At the proximal end of the
nail the central wire may provide threads which correspond to the
interior threads of the nut.
When the nut is tightened a sliding of the proximal section and
distal section on the first and second transverse abutments
respectively may be produced. If the intramedullary channel of the
femur has a larger interior diameter than the intramedullary nail,
the proximal section and distal section may expand transversely to
the longitudinal axis until fixation of the bone fragments may be
achieved. This radial expansion may be possible because the first
and second transverse abutments may enclose an angle of between
about 5.degree. and 85.degree. with the longitudinal axis, and
applying a force in the axial direction by means of tightening the
nut may cause the proximal section, the middle section and the
distal section to move or slide on the abutments providing a
sliding component generally orthogonal to the longitudinal axis
which may cause a radial expansion of the intramedullary nail.
Additionally, the middle section may provide sharp radial teeth
which may prevent axial displacement of the bone fragments after
fixation of the nail.
In yet another embodiment, the intramedullary nail may comprise
three elements: a nut with a head and a conical tip; a central wire
with a cone like distal end; and, a hollow intramedullary nail. The
ends of the intramedullary nail may be provided with a plurality of
cuts which may form contact studs that are radially expandable
within the intramedullary channel of the bone. The central wire may
run through the hollow channel of the intramedullary nail and--at
its proximal end--may have threads which correspond to the interior
threads of the nut. When the nut is tightened the distance between
the conical tip of the nut and the cone like distal end of the
central wire may be shortened, so that the contact studs of the
intramedullary nail are expanded by means of the radial forces
caused by the axial displacement of the cones. This expansion of
the intramedullary nail proximally and distally may produce
fixation of the bone fragments of a long bone such as a femur.
In general, an exemplary embodiment of the intramedullary nail for
fixation of bone fractures may have a head, a tip and a
longitudinal axis, characterized in that: a first radially
expandable section may be provided in the proximal section adjacent
to the head of the intramedullary nail; a second radially
expandable section may be provided in the distal section adjacent
to the tip of the intramedullary nail; and a non-expandable middle
section may be provided between two radially expandable sections of
the intramedullary nail. The exemplary embodiment may further be
characterized in that the head may be provided with a distraction
mechanism, by means of which two radially expandable sections are
distractible transverse to the longitudinal axis of the device.
Another exemplary embodiment may be characterized in that the
intramedulary nail comprises a core and at least two slotted
tubular pieces that provide the first and second radially
expandable sections. The intramedullary nail also may be
characterized in that the core provides a middle section--with a
minor diameter--and a an end section adjacent to the tip--with a
larger diameter--whereby these two sections are separated by an
annular abutment. The intramedullary nail may be further
characterized in that the slotted tubular pieces are configured
slidable on the middle section and prevented from sliding on the
end section towards the tip by means of the annular abutment.
In another embodiment of the intramedullary nail, the nail may be
characterized in that it comprises at least one unslotted tubular
piece providing the non-expandable middle section. The
intramedullary nail may be characterized in that the distraction
mechanism comprises a thread on the core adjacent to the head and a
nut with an interior thread corresponding with thread. For example,
the intramedullary nail may be characterized in that said
non-expandable section of the intramedullary nail has a length in
the range of 10 mm to 25 mm. In another example, the intramedullary
nail may be characterized in that said non-expandable section of
the intramedullary nail has a length in the range of 15 to 22
mm.
In another embodiment, the intramedullary nail may be characterized
in that the tubular pieces are slid over the core in the sequence:
a slotted tubular piece, an unslotted tubular piece, a slotted
tubular piece and an unslotted tubular piece and at last the nut is
screwed over the thread. The intramedullary nail may be further
characterized in that the nut comprises means for engagement of a
driving means. The intramedullary nail may also be characterized in
that the core comprises means for engagement of a holding means.
The intramedullary nail also may be characterized in that the means
for engagement of a driving means are hexagonal sides. Another
embodiment of the intramedullary nail may be characterized in that
the means for engagement of a holding means is a slot.
In another embodiment, the intramedullary nail may be characterized
in that it comprises a hollow sleeve extending along the
longitudinal axis and surrounding a locking element coaxially to
the longitudinal axis. The intramedullary nail may be characterized
in that the locking element comprises a shaft with a thread in the
proximal section and in the distal section a projection forming an
abutment. The intramedullary nail may further be characterized in
that in the distal section the sleeve provides a slot penetrating
the side wall through to the bore such that the projection of the
locking element may slide within said slot in the direction of the
longitudinal axis.
In another embodiment, the intramedullary nail may be characterized
in that it further comprises at least two slotted tubular pieces
that provide the first and second radially expandable sections.
Additionally, the intramedullary nail may be characterized in that
the slotted tubular pieces are configured slidable on the sleeve
and prevented from sliding on the end section towards the tip by
means of the abutment. The intramedullary nail may also be
characterized in that it comprises at least one unslotted tubular
piece providing the non-expandable middle section.
In another embodiment the intramedullary nail may be characterized
in that the distraction mechanism comprises a thread on the locking
element adjacent to the head and a nut with an interior thread
corresponding with thread. The intramedullary nail may also be
characterized in that the nut comprises means for engagement of a
driving means.
In another embodiment, the intramedullary nail may be characterized
in that the locking element comprises means for engagement of a
holding means. In addition, the intramedullary nail may be
characterized in that the distraction mechanism comprises a thread
on the locking element adjacent to the head and an end cap with an
interior thread corresponding with the thread. The intramedullary
nail may be characterized in that the end cap comprises means for
engagement of a driving means. The intramedullary nail may be
characterized in that the locking element comprises means for
engagement of a holding means. The intramedullary nail may be
characterized in that it comprises a nut, a hollow proximal
section, a hollow middle section, a hollow distal section, and a
central wire 54, whereby: contact between the proximal section and
the middle section may be represented by transverse abutments
(relative to the longitudinal axis 3); contact between middle
section and distal section is represented by transverse abutments
(relative to the longitudinal axis 3); the central wire may be
fixed in the distal section and may run through the hollow channel
of sections; at its proximal end the central wire may have threads
which correspond to the interior threads of the nut; and the
transverse abutments are configured at an angle of between
0.1.degree. and 89.9.degree. with the longitudinal axis such that
upon applying a force in the axial direction by means of tightening
the nut the proximal section, the middle section and the distal
section also provide a sliding component orthogonally to the
longitudinal axis on the abutments.
In another embodiment, the intramedullary nail may be characterized
in that the middle section provides sharp radial teeth preventing
axial displacement of the bone fragments after its fixation. The
intramedullary nail also may be characterized in that the
distraction mechanism comprises a thread on the wire adjacent to
the head and the nut with an interior thread corresponding with the
thread. The intramedullary nail may be characterized in that the
nut comprises means for engagement of a driving means.
Additionally, the intramedullary nail may be characterized in that
the wire comprises means for engagement of a holding means when the
nut is tightened.
In another embodiment, the intramedullary nail may be characterized
in that it comprises a nut with head and conical tip, a central
wire with a cone like distal end and a hollow intramedullary nail.
The intramedullary nail may be further characterized in that the
ends of the intramedullary nail are provided with a plurality of
cuts while the central wire runs through the hollow channel of the
intramedullary nail and--at its proximal end--has threads which
correspond to the interior threads of the nut. The intramedullary
nail may also be characterized in that the nut comprises means for
engagement of a driving means. The intramedullary nail may also be
characterized in that the central wire comprises means for
engagement of a holding means when the nut is tightened.
While various descriptions of the present invention are described
above, it should be understood that the various features can be
used singly or in any combination thereof. Therefore, this
invention is not to be limited to only the specifically preferred
embodiments depicted herein. For instance, other suitable
structures for engagement of a holding means such as a hex or other
shaped socket or recess may be employed. Further, it should be
understood that variations and modifications within the spirit and
scope of the invention may occur to those skilled in the art to
which the invention pertains. Accordingly, all expedient
modifications readily attainable by one versed in the art from the
disclosure set forth herein that are within the scope and spirit of
the present invention are to be included as further embodiments of
the present invention. The scope of the present invention is
accordingly defined as set forth in the appended claims.
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